Further methods for producing a rim hole are known from the state of the art. For example, in DE 89 03 243 a piercing is disclosed that connects several machined parts lying on top of each other without a rivet. The machined parts are in that case each provided in a preceding work step with round holes. In doing so, the hole of a machined part lying on the outside is smaller than the holes of the other machined parts. For forming a rim hole, the edge area of the smaller hole of the machined part on the outside that covers the larger holes of the other machined parts is pressed through the holes of the other machined parts. This rim hole protrudes over the outside surface of the other machined part lying on the outside and is subsequently flanged.
A method of the type cited above as a method for joining plates is also known from DE 40 35 210 A1. In the latter, the plates to be connected are likewise punched individually in a previous work step. The plate constituting the rim hole is left un-punched. A rim hole is produced by pressing a clipping punch through work pieces piled against a pressure plate, whereby the material of the un-punched plate is pulled through the pre-drilled holes of the other plates and opens out on the other side of the plates.
In the supplemental application DE 42 02 279 A1 accompanying DE 40 35 210 A1 quoted above, a block punch is additionally used which flanges the spread-outs and thus creates a tight connection.
A disadvantage with known methods is that the machined parts or plates to be connected must be predrilled individually in a separate work step. When drilling is accomplished, a decision must be made whether the machined part or plate in question forms the rim hole, in which case a small drill hole or no drill hole is made, or whether the rim hole is pressed through the machined part or plate in question, in which case larger holes must be made. Methods of this kind are unprofitable due to the extra work steps and due to the different drill holes of the machined parts or plates, depending on intended usage, it is cumbersome and prone to error.
In order for the drill holes separately produced in each plate to meet up exactly to produce the rim hole, the sum tolerance of the drill hole position must be kept precisely. For this, however, expensive machinery and trained personnel are required.